Identifying the relationship between fat oxidation and insulin resistance (IR) may provide vital clues to the mechanisms behind the development of metabolic disease in prepubertal children. The purpose of this study was to examine the association of fat oxidation with insulin resistance (IR) and insulin sensitivity (SI) in prepubertal children. A total of 34 prepubertal 7-9 year olds (18 females, 16 males, 13 non-Caucasian, 21 Caucasian, 8.0±0.8 years, 36.5±12.1 kg) were observed. Subjects participated in indirect calorimetry to obtain respiratory quotient (RQ) and a blood test to obtain fasting insulin and glucose to calculate IR by homeostatic model assessment (HOMA). A subset (n=16) participated in Frequently Sampled Intravenous Glucose Tolerance Testing (FSIGTT) to obtain insulin sensitivity. Pearson correlations between RQ and IR and RQ and SI were performed. Partial correlations with respect to physical activity, breastfeeding, and birth weight were also performed. A general linear model was used to examine RQ with IR, and separately SI with respect to physical activity, breastfeeding, birth weight, race and sex. Respiratory quotient and IR were significantly associated when adjusted for physical activity, sex and race and breastfeeding, sex and race. In regards to birth weight, RQ and IR were significantly associated when adjusted for breastfeeding, birth weight, and race, but not when breastfeeding was removed from the model. The results of this study suggest lack of physical activity and breastfeeding may be the most influential risk for factors in the development of IR via a mechanism of impaired fat oxidation. Further research is needed to examine the role of physical activity, breastfeeding, and birth weight on fat oxidation and the development of insulin resistance in prepubertal children, however, the results of this study support the promotion of physical activity, breastfeeding, and good maternal nutrition.

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